fs/ext4/dir.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  linux/fs/ext4/dir.c
   4  *
   5  * Copyright (C) 1992, 1993, 1994, 1995
   6  * Remy Card (card@masi.ibp.fr)
   7  * Laboratoire MASI - Institut Blaise Pascal
   8  * Universite Pierre et Marie Curie (Paris VI)
   9  *
  10  *  from
  11  *
  12  *  linux/fs/minix/dir.c
  13  *
  14  *  Copyright (C) 1991, 1992  Linus Torvalds
  15  *
  16  *  ext4 directory handling functions
  17  *
  18  *  Big-endian to little-endian byte-swapping/bitmaps by
  19  *        David S. Miller (davem@caip.rutgers.edu), 1995
  20  *
  21  * Hash Tree Directory indexing (c) 2001  Daniel Phillips
  22  *
  23  */
  24
  25 #include <linux/fs.h>
  26 #include <linux/buffer_head.h>
  27 #include <linux/slab.h>
  28 #include <linux/iversion.h>
  29 #include <linux/unicode.h>
  30 #include "ext4.h"
  31 #include "xattr.h"
  32
  33 static int ext4_dx_readdir(struct file *, struct dir_context *);
  34
  35 /**
  36  * is_dx_dir() - check if a directory is using htree indexing
  37  * @inode: directory inode
  38  *
  39  * Check if the given dir-inode refers to an htree-indexed directory
  40  * (or a directory which could potentially get converted to use htree
  41  * indexing).
  42  *
  43  * Return 1 if it is a dx dir, 0 if not
  44  */
  45 static int is_dx_dir(struct inode *inode)
  46 {
  47         struct super_block *sb = inode->i_sb;
  48
  49         if (ext4_has_feature_dir_index(inode->i_sb) &&
  50             ((ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) ||
  51              ((inode->i_size >> sb->s_blocksize_bits) == 1) ||
  52              ext4_has_inline_data(inode)))
  53                 return 1;
  54
  55         return 0;
  56 }
  57
  58 static bool is_fake_dir_entry(struct ext4_dir_entry_2 *de)
  59 {
  60         /* Check if . or .. , or skip if namelen is 0 */
  61         if ((de->name_len > 0) && (de->name_len <= 2) && (de->name[0] == '.') &&
  62             (de->name[1] == '.' || de->name[1] == '\0'))
  63                 return true;
  64         /* Check if this is a csum entry */
  65         if (de->file_type == EXT4_FT_DIR_CSUM)
  66                 return true;
  67         return false;
  68 }
  69
  70 /*
  71  * Return 0 if the directory entry is OK, and 1 if there is a problem
  72  *
  73  * Note: this is the opposite of what ext2 and ext3 historically returned...
  74  *
  75  * bh passed here can be an inode block or a dir data block, depending
  76  * on the inode inline data flag.
  77  */
  78 int __ext4_check_dir_entry(const char *function, unsigned int line,
  79                            struct inode *dir, struct file *filp,
  80                            struct ext4_dir_entry_2 *de,
  81                            struct buffer_head *bh, char *buf, int size,
  82                            unsigned int offset)
  83 {
  84         const char *error_msg = NULL;
  85         const int rlen = ext4_rec_len_from_disk(de->rec_len,
  86                                                 dir->i_sb->s_blocksize);
  87         const int next_offset = ((char *) de - buf) + rlen;
  88         bool fake = is_fake_dir_entry(de);
  89         bool has_csum = ext4_has_feature_metadata_csum(dir->i_sb);
  90
  91         if (unlikely(rlen < ext4_dir_rec_len(1, fake ? NULL : dir)))
  92                 error_msg = "rec_len is smaller than minimal";
  93         else if (unlikely(rlen % 4 != 0))
  94                 error_msg = "rec_len % 4 != 0";
  95         else if (unlikely(rlen < ext4_dir_rec_len(de->name_len,
  96                                                         fake ? NULL : dir)))
  97                 error_msg = "rec_len is too small for name_len";
  98         else if (unlikely(next_offset > size))
  99                 error_msg = "directory entry overrun";
 100         else if (unlikely(next_offset > size - ext4_dir_rec_len(1,
 101                                                   has_csum ? NULL : dir) &&
 102                           next_offset != size))
 103                 error_msg = "directory entry too close to block end";
 104         else if (unlikely(le32_to_cpu(de->inode) >
 105                         le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)))
 106                 error_msg = "inode out of bounds";
 107         else if (unlikely(next_offset == size && de->name_len == 1 &&
 108                           de->name[0] == '.'))
 109                 error_msg = "'.' directory cannot be the last in data block";
 110         else
 111                 return 0;
 112
 113         if (filp)
 114                 ext4_error_file(filp, function, line, bh->b_blocknr,
 115                                 "bad entry in directory: %s - offset=%u, "
 116                                 "inode=%u, rec_len=%d, size=%d fake=%d",
 117                                 error_msg, offset, le32_to_cpu(de->inode),
 118                                 rlen, size, fake);
 119         else
 120                 ext4_error_inode(dir, function, line, bh->b_blocknr,
 121                                 "bad entry in directory: %s - offset=%u, "
 122                                 "inode=%u, rec_len=%d, size=%d fake=%d",
 123                                  error_msg, offset, le32_to_cpu(de->inode),
 124                                  rlen, size, fake);
 125
 126         return 1;
 127 }
 128
 129 static int ext4_readdir(struct file *file, struct dir_context *ctx)
 130 {
 131         unsigned int offset;
 132         int i;
 133         struct ext4_dir_entry_2 *de;
 134         int err;
 135         struct inode *inode = file_inode(file);
 136         struct super_block *sb = inode->i_sb;
 137         struct buffer_head *bh = NULL;
 138         struct fscrypt_str fstr = FSTR_INIT(NULL, 0);
 139         struct dir_private_info *info = file->private_data;
 140
 141         err = fscrypt_prepare_readdir(inode);
 142         if (err)
 143                 return err;
 144
 145         if (is_dx_dir(inode)) {
 146                 err = ext4_dx_readdir(file, ctx);
 147                 if (err != ERR_BAD_DX_DIR)
 148                         return err;
 149
 150                 /* Can we just clear INDEX flag to ignore htree information? */
 151                 if (!ext4_has_feature_metadata_csum(sb)) {
 152                         /*
 153                          * We don't set the inode dirty flag since it's not
 154                          * critical that it gets flushed back to the disk.
 155                          */
 156                         ext4_clear_inode_flag(inode, EXT4_INODE_INDEX);
 157                 }
 158         }
 159
 160         if (ext4_has_inline_data(inode)) {
 161                 int has_inline_data = 1;
 162                 err = ext4_read_inline_dir(file, ctx,
 163                                            &has_inline_data);
 164                 if (has_inline_data)
 165                         return err;
 166         }
 167
 168         if (IS_ENCRYPTED(inode)) {
 169                 err = fscrypt_fname_alloc_buffer(EXT4_NAME_LEN, &fstr);
 170                 if (err < 0)
 171                         return err;
 172         }
 173
 174         while (ctx->pos < inode->i_size) {
 175                 struct ext4_map_blocks map;
 176
 177                 if (fatal_signal_pending(current)) {
 178                         err = -ERESTARTSYS;
 179                         goto errout;
 180                 }
 181                 cond_resched();
 182                 offset = ctx->pos & (sb->s_blocksize - 1);
 183                 map.m_lblk = ctx->pos >> EXT4_BLOCK_SIZE_BITS(sb);
 184                 map.m_len = 1;
 185                 err = ext4_map_blocks(NULL, inode, &map, 0);
 186                 if (err == 0) {
 187                         /* m_len should never be zero but let's avoid
 188                          * an infinite loop if it somehow is */
 189                         if (map.m_len == 0)
 190                                 map.m_len = 1;
 191                         ctx->pos += map.m_len * sb->s_blocksize;
 192                         continue;
 193                 }
 194                 if (err > 0) {
 195                         pgoff_t index = map.m_pblk >>
 196                                         (PAGE_SHIFT - inode->i_blkbits);
 197                         if (!ra_has_index(&file->f_ra, index))
 198                                 page_cache_sync_readahead(
 199                                         sb->s_bdev->bd_mapping,
 200                                         &file->f_ra, file,
 201                                         index, 1);
 202                         file->f_ra.prev_pos = (loff_t)index << PAGE_SHIFT;
 203                         bh = ext4_bread(NULL, inode, map.m_lblk, 0);
 204                         if (IS_ERR(bh)) {
 205                                 err = PTR_ERR(bh);
 206                                 bh = NULL;
 207                                 goto errout;
 208                         }
 209                 }
 210
 211                 if (!bh) {
 212                         /* corrupt size?  Maybe no more blocks to read */
 213                         if (ctx->pos > inode->i_blocks << 9)
 214                                 break;
 215                         ctx->pos += sb->s_blocksize - offset;
 216                         continue;
 217                 }
 218
 219                 /* Check the checksum */
 220                 if (!buffer_verified(bh) &&
 221                     !ext4_dirblock_csum_verify(inode, bh)) {
 222                         EXT4_ERROR_FILE(file, 0, "directory fails checksum "
 223                                         "at offset %llu",
 224                                         (unsigned long long)ctx->pos);
 225                         ctx->pos += sb->s_blocksize - offset;
 226                         brelse(bh);
 227                         bh = NULL;
 228                         continue;
 229                 }
 230                 set_buffer_verified(bh);
 231
 232                 /* If the dir block has changed since the last call to
 233                  * readdir(2), then we might be pointing to an invalid
 234                  * dirent right now.  Scan from the start of the block
 235                  * to make sure. */
 236                 if (!inode_eq_iversion(inode, info->cookie)) {
 237                         for (i = 0; i < sb->s_blocksize && i < offset; ) {
 238                                 de = (struct ext4_dir_entry_2 *)
 239                                         (bh->b_data + i);
 240                                 /* It's too expensive to do a full
 241                                  * dirent test each time round this
 242                                  * loop, but we do have to test at
 243                                  * least that it is non-zero.  A
 244                                  * failure will be detected in the
 245                                  * dirent test below. */
 246                                 if (ext4_rec_len_from_disk(de->rec_len,
 247                                         sb->s_blocksize) < ext4_dir_rec_len(1,
 248                                                                         inode))
 249                                         break;
 250                                 i += ext4_rec_len_from_disk(de->rec_len,
 251                                                             sb->s_blocksize);
 252                         }
 253                         offset = i;
 254                         ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1))
 255                                 | offset;
 256                         info->cookie = inode_query_iversion(inode);
 257                 }
 258
 259                 while (ctx->pos < inode->i_size
 260                        && offset < sb->s_blocksize) {
 261                         de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
 262                         if (ext4_check_dir_entry(inode, file, de, bh,
 263                                                  bh->b_data, bh->b_size,
 264                                                  offset)) {
 265                                 /*
 266                                  * On error, skip to the next block
 267                                  */
 268                                 ctx->pos = (ctx->pos |
 269                                                 (sb->s_blocksize - 1)) + 1;
 270                                 break;
 271                         }
 272                         offset += ext4_rec_len_from_disk(de->rec_len,
 273                                         sb->s_blocksize);
 274                         if (le32_to_cpu(de->inode)) {
 275                                 if (!IS_ENCRYPTED(inode)) {
 276                                         if (!dir_emit(ctx, de->name,
 277                                             de->name_len,
 278                                             le32_to_cpu(de->inode),
 279                                             get_dtype(sb, de->file_type)))
 280                                                 goto done;
 281                                 } else {
 282                                         int save_len = fstr.len;
 283                                         struct fscrypt_str de_name =
 284                                                         FSTR_INIT(de->name,
 285                                                                 de->name_len);
 286                                         u32 hash;
 287                                         u32 minor_hash;
 288
 289                                         if (IS_CASEFOLDED(inode)) {
 290                                                 hash = EXT4_DIRENT_HASH(de);
 291                                                 minor_hash = EXT4_DIRENT_MINOR_HASH(de);
 292                                         } else {
 293                                                 hash = 0;
 294                                                 minor_hash = 0;
 295                                         }
 296
 297                                         /* Directory is encrypted */
 298                                         err = fscrypt_fname_disk_to_usr(inode,
 299                                                 hash, minor_hash, &de_name, &fstr);
 300                                         de_name = fstr;
 301                                         fstr.len = save_len;
 302                                         if (err)
 303                                                 goto errout;
 304                                         if (!dir_emit(ctx,
 305                                             de_name.name, de_name.len,
 306                                             le32_to_cpu(de->inode),
 307                                             get_dtype(sb, de->file_type)))
 308                                                 goto done;
 309                                 }
 310                         }
 311                         ctx->pos += ext4_rec_len_from_disk(de->rec_len,
 312                                                 sb->s_blocksize);
 313                 }
 314                 if ((ctx->pos < inode->i_size) && !dir_relax_shared(inode))
 315                         goto done;
 316                 brelse(bh);
 317                 bh = NULL;
 318         }
 319 done:
 320         err = 0;
 321 errout:
 322         fscrypt_fname_free_buffer(&fstr);
 323         brelse(bh);
 324         return err;
 325 }
 326
 327 static inline int is_32bit_api(void)
 328 {
 329 #ifdef CONFIG_COMPAT
 330         return in_compat_syscall();
 331 #else
 332         return (BITS_PER_LONG == 32);
 333 #endif
 334 }
 335
 336 /*
 337  * These functions convert from the major/minor hash to an f_pos
 338  * value for dx directories
 339  *
 340  * Upper layer (for example NFS) should specify FMODE_32BITHASH or
 341  * FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted
 342  * directly on both 32-bit and 64-bit nodes, under such case, neither
 343  * FMODE_32BITHASH nor FMODE_64BITHASH is specified.
 344  */
 345 static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor)
 346 {
 347         if ((filp->f_mode & FMODE_32BITHASH) ||
 348             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 349                 return major >> 1;
 350         else
 351                 return ((__u64)(major >> 1) << 32) | (__u64)minor;
 352 }
 353
 354 static inline __u32 pos2maj_hash(struct file *filp, loff_t pos)
 355 {
 356         if ((filp->f_mode & FMODE_32BITHASH) ||
 357             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 358                 return (pos << 1) & 0xffffffff;
 359         else
 360                 return ((pos >> 32) << 1) & 0xffffffff;
 361 }
 362
 363 static inline __u32 pos2min_hash(struct file *filp, loff_t pos)
 364 {
 365         if ((filp->f_mode & FMODE_32BITHASH) ||
 366             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 367                 return 0;
 368         else
 369                 return pos & 0xffffffff;
 370 }
 371
 372 /*
 373  * Return 32- or 64-bit end-of-file for dx directories
 374  */
 375 static inline loff_t ext4_get_htree_eof(struct file *filp)
 376 {
 377         if ((filp->f_mode & FMODE_32BITHASH) ||
 378             (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
 379                 return EXT4_HTREE_EOF_32BIT;
 380         else
 381                 return EXT4_HTREE_EOF_64BIT;
 382 }
 383
 384
 385 /*
 386  * ext4_dir_llseek() calls generic_file_llseek_size to handle htree
 387  * directories, where the "offset" is in terms of the filename hash
 388  * value instead of the byte offset.
 389  *
 390  * Because we may return a 64-bit hash that is well beyond offset limits,
 391  * we need to pass the max hash as the maximum allowable offset in
 392  * the htree directory case.
 393  *
 394  * For non-htree, ext4_llseek already chooses the proper max offset.
 395  */
 396 static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence)
 397 {
 398         struct inode *inode = file->f_mapping->host;
 399         struct dir_private_info *info = file->private_data;
 400         int dx_dir = is_dx_dir(inode);
 401         loff_t ret, htree_max = ext4_get_htree_eof(file);
 402
 403         if (likely(dx_dir))
 404                 ret = generic_file_llseek_size(file, offset, whence,
 405                                                     htree_max, htree_max);
 406         else
 407                 ret = ext4_llseek(file, offset, whence);
 408         info->cookie = inode_peek_iversion(inode) - 1;
 409         return ret;
 410 }
 411
 412 /*
 413  * This structure holds the nodes of the red-black tree used to store
 414  * the directory entry in hash order.
 415  */
 416 struct fname {
 417         __u32           hash;
 418         __u32           minor_hash;
 419         struct rb_node  rb_hash;
 420         struct fname    *next;
 421         __u32           inode;
 422         __u8            name_len;
 423         __u8            file_type;
 424         char            name[] __counted_by(name_len);
 425 };
 426
 427 /*
 428  * This function implements a non-recursive way of freeing all of the
 429  * nodes in the red-black tree.
 430  */
 431 static void free_rb_tree_fname(struct rb_root *root)
 432 {
 433         struct fname *fname, *next;
 434
 435         rbtree_postorder_for_each_entry_safe(fname, next, root, rb_hash)
 436                 while (fname) {
 437                         struct fname *old = fname;
 438                         fname = fname->next;
 439                         kfree(old);
 440                 }
 441
 442         *root = RB_ROOT;
 443 }
 444
 445 static void ext4_htree_init_dir_info(struct file *filp, loff_t pos)
 446 {
 447         struct dir_private_info *p = filp->private_data;
 448
 449         if (is_dx_dir(file_inode(filp)) && !p->initialized) {
 450                 p->curr_hash = pos2maj_hash(filp, pos);
 451                 p->curr_minor_hash = pos2min_hash(filp, pos);
 452                 p->initialized = true;
 453         }
 454 }
 455
 456 void ext4_htree_free_dir_info(struct dir_private_info *p)
 457 {
 458         free_rb_tree_fname(&p->root);
 459         kfree(p);
 460 }
 461
 462 /*
 463  * Given a directory entry, enter it into the fname rb tree.
 464  *
 465  * When filename encryption is enabled, the dirent will hold the
 466  * encrypted filename, while the htree will hold decrypted filename.
 467  * The decrypted filename is passed in via ent_name.  parameter.
 468  */
 469 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
 470                              __u32 minor_hash,
 471                             struct ext4_dir_entry_2 *dirent,
 472                             struct fscrypt_str *ent_name)
 473 {
 474         struct rb_node **p, *parent = NULL;
 475         struct fname *fname, *new_fn;
 476         struct dir_private_info *info;
 477
 478         info = dir_file->private_data;
 479         p = &info->root.rb_node;
 480
 481         /* Create and allocate the fname structure */
 482         new_fn = kzalloc(struct_size(new_fn, name, ent_name->len + 1),
 483                          GFP_KERNEL);
 484         if (!new_fn)
 485                 return -ENOMEM;
 486         new_fn->hash = hash;
 487         new_fn->minor_hash = minor_hash;
 488         new_fn->inode = le32_to_cpu(dirent->inode);
 489         new_fn->name_len = ent_name->len;
 490         new_fn->file_type = dirent->file_type;
 491         memcpy(new_fn->name, ent_name->name, ent_name->len);
 492
 493         while (*p) {
 494                 parent = *p;
 495                 fname = rb_entry(parent, struct fname, rb_hash);
 496
 497                 /*
 498                  * If the hash and minor hash match up, then we put
 499                  * them on a linked list.  This rarely happens...
 500                  */
 501                 if ((new_fn->hash == fname->hash) &&
 502                     (new_fn->minor_hash == fname->minor_hash)) {
 503                         new_fn->next = fname->next;
 504                         fname->next = new_fn;
 505                         return 0;
 506                 }
 507
 508                 if (new_fn->hash < fname->hash)
 509                         p = &(*p)->rb_left;
 510                 else if (new_fn->hash > fname->hash)
 511                         p = &(*p)->rb_right;
 512                 else if (new_fn->minor_hash < fname->minor_hash)
 513                         p = &(*p)->rb_left;
 514                 else /* if (new_fn->minor_hash > fname->minor_hash) */
 515                         p = &(*p)->rb_right;
 516         }
 517
 518         rb_link_node(&new_fn->rb_hash, parent, p);
 519         rb_insert_color(&new_fn->rb_hash, &info->root);
 520         return 0;
 521 }
 522
 523
 524
 525 /*
 526  * This is a helper function for ext4_dx_readdir.  It calls filldir
 527  * for all entries on the fname linked list.  (Normally there is only
 528  * one entry on the linked list, unless there are 62 bit hash collisions.)
 529  */
 530 static int call_filldir(struct file *file, struct dir_context *ctx,
 531                         struct fname *fname)
 532 {
 533         struct dir_private_info *info = file->private_data;
 534         struct inode *inode = file_inode(file);
 535         struct super_block *sb = inode->i_sb;
 536
 537         if (!fname) {
 538                 ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: comm %s: "
 539                          "called with null fname?!?", __func__, __LINE__,
 540                          inode->i_ino, current->comm);
 541                 return 0;
 542         }
 543         ctx->pos = hash2pos(file, fname->hash, fname->minor_hash);
 544         while (fname) {
 545                 if (!dir_emit(ctx, fname->name,
 546                                 fname->name_len,
 547                                 fname->inode,
 548                                 get_dtype(sb, fname->file_type))) {
 549                         info->extra_fname = fname;
 550                         return 1;
 551                 }
 552                 fname = fname->next;
 553         }
 554         return 0;
 555 }
 556
 557 static int ext4_dx_readdir(struct file *file, struct dir_context *ctx)
 558 {
 559         struct dir_private_info *info = file->private_data;
 560         struct inode *inode = file_inode(file);
 561         struct fname *fname;
 562         int ret = 0;
 563
 564         ext4_htree_init_dir_info(file, ctx->pos);
 565
 566         if (ctx->pos == ext4_get_htree_eof(file))
 567                 return 0;       /* EOF */
 568
 569         /* Some one has messed with f_pos; reset the world */
 570         if (info->last_pos != ctx->pos) {
 571                 free_rb_tree_fname(&info->root);
 572                 info->curr_node = NULL;
 573                 info->extra_fname = NULL;
 574                 info->curr_hash = pos2maj_hash(file, ctx->pos);
 575                 info->curr_minor_hash = pos2min_hash(file, ctx->pos);
 576         }
 577
 578         /*
 579          * If there are any leftover names on the hash collision
 580          * chain, return them first.
 581          */
 582         if (info->extra_fname) {
 583                 if (call_filldir(file, ctx, info->extra_fname))
 584                         goto finished;
 585                 info->extra_fname = NULL;
 586                 goto next_node;
 587         } else if (!info->curr_node)
 588                 info->curr_node = rb_first(&info->root);
 589
 590         while (1) {
 591                 /*
 592                  * Fill the rbtree if we have no more entries,
 593                  * or the inode has changed since we last read in the
 594                  * cached entries.
 595                  */
 596                 if ((!info->curr_node) ||
 597                     !inode_eq_iversion(inode, info->cookie)) {
 598                         info->curr_node = NULL;
 599                         free_rb_tree_fname(&info->root);
 600                         info->cookie = inode_query_iversion(inode);
 601                         ret = ext4_htree_fill_tree(file, info->curr_hash,
 602                                                    info->curr_minor_hash,
 603                                                    &info->next_hash);
 604                         if (ret < 0)
 605                                 goto finished;
 606                         if (ret == 0) {
 607                                 ctx->pos = ext4_get_htree_eof(file);
 608                                 break;
 609                         }
 610                         info->curr_node = rb_first(&info->root);
 611                 }
 612
 613                 fname = rb_entry(info->curr_node, struct fname, rb_hash);
 614                 info->curr_hash = fname->hash;
 615                 info->curr_minor_hash = fname->minor_hash;
 616                 if (call_filldir(file, ctx, fname))
 617                         break;
 618         next_node:
 619                 info->curr_node = rb_next(info->curr_node);
 620                 if (info->curr_node) {
 621                         fname = rb_entry(info->curr_node, struct fname,
 622                                          rb_hash);
 623                         info->curr_hash = fname->hash;
 624                         info->curr_minor_hash = fname->minor_hash;
 625                 } else {
 626                         if (info->next_hash == ~0) {
 627                                 ctx->pos = ext4_get_htree_eof(file);
 628                                 break;
 629                         }
 630                         info->curr_hash = info->next_hash;
 631                         info->curr_minor_hash = 0;
 632                 }
 633         }
 634 finished:
 635         info->last_pos = ctx->pos;
 636         return ret < 0 ? ret : 0;
 637 }
 638
 639 static int ext4_release_dir(struct inode *inode, struct file *filp)
 640 {
 641         if (filp->private_data)
 642                 ext4_htree_free_dir_info(filp->private_data);
 643
 644         return 0;
 645 }
 646
 647 int ext4_check_all_de(struct inode *dir, struct buffer_head *bh, void *buf,
 648                       int buf_size)
 649 {
 650         struct ext4_dir_entry_2 *de;
 651         int rlen;
 652         unsigned int offset = 0;
 653         char *top;
 654
 655         de = buf;
 656         top = buf + buf_size;
 657         while ((char *) de < top) {
 658                 if (ext4_check_dir_entry(dir, NULL, de, bh,
 659                                          buf, buf_size, offset))
 660                         return -EFSCORRUPTED;
 661                 rlen = ext4_rec_len_from_disk(de->rec_len, buf_size);
 662                 de = (struct ext4_dir_entry_2 *)((char *)de + rlen);
 663                 offset += rlen;
 664         }
 665         if ((char *) de > top)
 666                 return -EFSCORRUPTED;
 667
 668         return 0;
 669 }
 670
 671 static int ext4_dir_open(struct inode *inode, struct file *file)
 672 {
 673         struct dir_private_info *info;
 674
 675         info = kzalloc(sizeof(*info), GFP_KERNEL);
 676         if (!info)
 677                 return -ENOMEM;
 678         file->private_data = info;
 679         return 0;
 680 }
 681
 682 const struct file_operations ext4_dir_operations = {
 683         .open           = ext4_dir_open,
 684         .llseek         = ext4_dir_llseek,
 685         .read           = generic_read_dir,
 686         .iterate_shared = ext4_readdir,
 687         .unlocked_ioctl = ext4_ioctl,
 688 #ifdef CONFIG_COMPAT
 689         .compat_ioctl   = ext4_compat_ioctl,
 690 #endif
 691         .fsync          = ext4_sync_file,
 692         .release        = ext4_release_dir,
 693 };